However, your cycle will probably differ from this pattern, perhaps significantly, which is why it's useful to mark changes on your own fertility chart.

Ideally, you should check your cervical mucus daily, possibly every time you go to the bathroom. If you rub some toilet paper or your fingers -- after washing your hands -- over the opening of your vagina, you should be able to detect cervical mucus. Examine the color and consistency between your fingers and make sure to record it.

Cervical Position and Ovulation

Another way of learning about where you are in your mentrual cycle is to examine the position of your cervix. If you insert two fingers into your vagina, you should feel the cervix at the end. Before ovulation, it should feel hard and dry, like the tip of a nose. During ovulation, you should notice that it seems to have shifted higher and that it feels softer and wetter. However, you should always make sure that your hands are clean before you start poking around. And since it may be hard to tell exactly what you're looking for, you may want to talk to your doctor first.

Tests and Devices to Predict Ovulation

Home tests and devices offer a different approach to monitoring your fertility cycle. Some people use these alongside traditional techniques while others use them as a substitute.

Ovulation Predictor Kits (OPKs) are available at most drugstores and cost about $20 to $75 a month. By testing the levels of luteinizing hormone (LH) in your urine, the kits can tell you when you're undergoing the surge in LH levels that precedes ovulation by 12 to 36 hours. Studies have found these kits more than 90% accurate.

The newest OPKs are digital. While a little more expensive, the advantage is that the display is easier to read. Instead of having to interpret those sometimes ambiguous pink lines, you get a clear symbol on the readout, like a smiley face.

Saliva or "Ferning" Microscopes use a different approach. These are small microscopes -- sometimes designed to look like lipstick cases -- for examining a sample of your saliva. As estrogen levels build up as you head toward ovulation, salt levels in your mucus increase, too. When the mucus is looked at under a microscope, the salt causes a pattern that looks like the leaves of a fern plant -- hence "ferning."

Manufacturers claim that by using the microscopes to examine your saliva -- and learning what to look for -- you can predict ovulation by 24-72 hours. They cost about $30 to $50, and, unlike many other ovulation tests, they don’t require additional expensive supplies. However, studies have not found them all that reliable. They don't seem to work for everyone, and the results can be hard to interpret.

Fertility Monitors can be very expensive, but they have a significant benefit. While most ovulation predictors only give you a fertile window of up to two days, these can predict up to six or seven days of potential fertility for each cycle.

They work in different ways. The Clearblue Easy Fertility Monitor measures the levels of LH as well as another hormone -- e3G -- in the urine. The results are easy to understand and displayed on a digital screen. They're also stored in the monitor's memory. Studies show it to be quite effective -- more than 90% accurate. The device itself costs $200, and the test strips are another $30 to $50 per month.

The Zetek OvaCue is another computerized monitor that uses a different approach. It checks levels of electrolytes in the saliva. It's easy to use (you just stick a sensor in your mouth), stores your data, and displays the results clearly. An optional vaginal sensor can be used to confirm ovulation. However, studies have produced conflicting results as to the effectiveness of the approach. The monitor costs $300 (or $400 with the additional sensor), but it does not require further supplies.

The OV-Watch is sensor that's worn like a wristwatch. According to its manufacturer, it can sense chemical changes on the skin that predict ovulation.

While these tests and devices may be helpful, keep in mind that they aren't perfect. If you have a medical condition like polycystic ovary syndrome (PCOS) or take regular medications, these tests and devices may not give accurate results. Since there are so many ovulation tests and monitors out there, it's always a good idea to ask your doctor which one you should try.